'Wàn néng yào shi' literally means 'ten-thousand-capable key' — a compound formed from 万 (wàn, 'ten thousand', used here hyperbolically to mean 'all' or 'every'), 能 (néng, 'able/capable'), and 钥匙 (yào shi, 'key'). It refers to a master key: a single key that can open multiple different locks, often used in hotels, office buildings, or by maintenance staff. Unlike ordinary keys, it bypasses individual lock mechanisms through specialized design.

In Chinese, the term is also used metaphorically to describe something that solves many problems at once — for example, a versatile tool, a universal solution, or even an influential person who can resolve various issues. However, its primary and most common usage remains literal and technical, especially in security, property management, and daily life contexts involving access control.